1. Technical Field
This disclosure relates to an optical disc recording medium used for recording information.
2. Description of Related Art
The optical disc recording medium is required to have a flat surface. Various methods have been known in order to manufacture an optical disc recording medium having a flat surface.
Japanese Laid-Open Patent Publication No. JP 2003-067990 A discloses an optical recording medium having a light transmission layer formed by a spin coating method. In an outer circumferential portion of a substrate of the optical recording medium, an inclined surface is formed such that the thickness of the substrate is gradually reduced as approaching the edge along the radial direction. As a result, a raised portion, which inevitably appears when using the resin coating of the conventional spin coating method, is accommodated by the inclined surface of the outer circumferential portion, and does not protrude from a surface of an information recording area of the light transmission layer.